Napoleon's spectacular career, which took him from the ranks of the impoverished nobility on the island of Corsica to ruler of territories that at their height stretched from the Elbe River to the Iberian Peninsula, had profound repercussions for the whole of Europe, including those states such as Britain which never came under direct Napoleonic rule. Like a number of other able military men such as Louis-Lazare Hoche, a former stable-boy, and Michel Ney, the son of a cooper, his rise was inconceivable without the collapse of the old regime and the French Revolution, which opened up careers to talent. Alongside his military abilities, it was his intelligence, ruthlessness, and charisma, as well as a sense of destiny, that were the personal qualities underpinning his rise to power.

Born in 1769 at Ajaccio in Corsica, an island that had only been transferred from Genoese to French sovereignty the previous year, he was always something of an outsider with a concomitant willingness to disregard established structures and to implement change on a radical scale. A child of the Enlightenment with a voracious appetite for books, he was interested in new ideas and remained a firm believer in rational government. His Corsican background also gave him a strong sense of the importance of family and of personal loyalty. As a result, he made extensive use of his relatives to rule his conquests, though always ensuring that they had little scope for independent action. And he was prepared to include in his regime men from a variety of backgrounds, including former members of the old regime nobility and Jacobin terrorists, so long as they demonstrated fidelity to him.

After a briefdalliance with Corsican independence, Napoleon's father had rallied to French rule as the best means of family advancement and he sent his son to the military college at Brienne in 1779. Five years later Napoleon moved to the elite Ecole Militaire at Paris. In 1785 he was commissioned into an artillery regiment, at the time an unfashionable branch of the military service despite the reforms to the artillery carried out by the gifted Inspector-General Jean-Baptiste Vaquette de Gribeauval, though it would be integral to the practice of Napoleonic warfare. He returned to Corsica at the outbreak of the revolution, but quickly became disenchanted with Corsican nationalism and moved, with his family, back to France. Here he associated himself with the Jacobin Club at Paris. The members of the club and its nationwide network of affiliated societies were at the forefront of radical action, and would be associated with the operation of the government of the Terror in 1793–1794. However, Napoleon was no populist and detested the disorder associated with many of the great journées of the revolution. His military abilities and the shortage of officers—six thousand had left the military by the end of 1791—ensured his rapid promotion. Following his skilful handling of the artillery at the siege of Toulon, which led to the port's recapture from the British, he was promoted to brigadier-general and commander-in-chief of the artillery of the Army of Italy at the age of only 24. However, his links with the Jacobins led to his brief imprisonment after the fall of Robespierre in July 1794 and the subsequent reaction against the Terror. His name was struck off the officer list when he refused an appointment that would have meant fighting inside France against the rebels in the Vendée, the department in the west of France which had been the focus of a counter-revolutionary uprising since February 1793. The wheel of fortune turned again the following year. Crucially, Napoleon benefitted from the patronage of Paul Barras, a corrupt but adroit politician. Barras ensured that Napoleon commanded the troops who, in October 1795, dispersed a royalist challenge to the Convention, the successor to the Legislative and the third of the elected assemblies to govern France, using the famous “whiff of grapeshot.” Napoleon was rewarded with command of the Army of the Interior. He married Barras's former mistress, Josephine, in March 1796, and two days later he left to take over command of the Army of Italy. It was in this role that he really made his name.

Napoleon transformed the demoralized Army of Italy and led it to a series of spectacular victories, at Lodi, Roveredo, Arcola, Rivoli, and elsewhere, over the Austrians and Piedmontese, forcing them to sign peace treaties at Leoben and Campo-Formio. He imposed terms upon the papacy and the Venetians and established sister republics in the north of the peninsula. Significantly, these political arrangements were made without reference to the Directory, the governing regime in France established in 1795 by the outgoing Convention. “I have tasted supremacy and I can no longer renounce it,” he commented to one associate (Parker 1971: 22). The death of Hoche left Napoleon as the revolution's preeminent general, and in 1797 he was given charge of the forces assembled for the invasion of England. Recognizing the impracticality of the project, he extricated himself from the command and instead led the expedition against Egypt. Designed to undermine Britain's commercial power by severing the link with India, the expedition was ultimately a military failure, despite local victories over the Mamluk armies. However, by the time of the French surrender Napoleon had already returned to France, his reputation intact and, indeed, bolstered by his shrewd use of propaganda and the focus upon the intellectual and cultural achievements of the expedition.

In Paris, Napoleon found the government riven by faction and lacking popular support. Invited by the Abbé Emmanuel-Joseph Sieyès—the leading political theoretician of the revolution—to play the part of the military strong man, Napoleon, with the key assistance of his brother Lucien, overthrew the Directory in the muddled coup of 18 Brumaire (November 9–10, 1799). As part of the new order, Napoleon became the first of three consuls, but he rapidly persuaded Sieyés and Roger Ducos to retire into private life, leaving himselfas the effective ruler of France, a situation that was confirmed when he became consul for life in 1802. Always concerned about the legitimacy of his rule, Napoleon had these changes of government approved by plebiscites. To consolidate his rule, he also embarked upon the second Italian campaign in 1800, defeating an Austrian army at Marengo. Further reverses in Germany led Austria to conclude the Peace of Lunéville in 1801, while Britain, confronted with the break-up of the Second Coalition, had little choice but to accede to the Peace of Amiens the following year.

The cessation often years of conflict, temporary though this proved to be, allowed Napoleon to embark upon a series of domestic reforms that would be continued even when hostilities resumed. A concordat with Pius VII restored the Catholic Church to France, albeit under close government supervision. This agreement drew the religious sting out of the counter-revolution and, together with a draconian use of the army, helped to restore public order to France. Administration was centralized and many aspects of a police state were introduced, but this overhaul enabled Napoleon to tap the country's reserves of wealth and manpower more effectively. Between 1800 and 1813 France furnished him with two million recruits. The Code Civil, published in 1804 and known after 1807 as the Code Napoléon, provided France with a single unified law code. A metallic currency replaced the revolution's paper assignats, the Bank of France was established, tax collection was reformed, and these measures, together with the ruthless exploitation of occupied territories, stabilized the state's finances. Although elementary and girls' education was neglected, secondary education was reformed to create a cadre of pupils who would serve as public officials and military officers. In 1804 Napoleon used the excuse of a royalist plot against his life to justify the establishment of an empire, crowning himself as its ruler on December 2 in the Cathedral of Notre Dame. Many of Napoleon's domestic reforms would be extended to the territories occupied by French forces.

Napoleonic rule was always contingent upon the continuing superiority of French arms. The Peace of Amiens fractured in May 1803 and Napoleon, having reorganized the structure of his forces, gathered the Grande ArmeIe at Boulogne for a cross-Channel assault against England. However, the invasion was abandoned as he marched his forces eastwards to deal with Austria and Russia, which had become increasingly concerned by Napoleonic policies in Italy, where Piedmont had been annexed and a new Kingdom of Italy, with Napoleon as its king, had been created. In a lightning campaign the emperor defeated the continental members of the Third Coalition: the Austrians at Ulm (October 20, 1805) and the Russo-Austrian armies at Austerlitz (December 2, 1805). The following year Napoleon reconfigured his German allies and satellite territories into the Confederation of the Rhine, a move that alarmed Prussia, which had held aloof from the Third Coalition, prompting her to ally with Russia. Prussia's armies were decisively beaten at Jena-Auerstädt (October 14, 1806). Russian forces inflicted serious losses on the French at Eylau (February 7, 1807), but four months later they were defeated at Friedland (June 14,1807). The tsar accepted peace terms at Tilsit, agreeing to enforce the Continental Blockade against British goods which had been established the previous year, and which was intended to bring Britain to her knees.

Napoleon stood at the height of his powers in the summer of 1807, though the empire would not reach its greatest territorial extent until 1810–1811 when some 44 million people in 130 departments were under imperial rule. Yet it was in 1807 that Napoleon's fortunes began to unravel. To secure his southern flank, he despatched a force to Portugal, which was proving a weak link in the Blockade, and the following year he replaced the Spanish king, Charles IV, with Joseph Bonaparte. The ensuing Peninsular War, fought against guerillas as well as shrewdly led Anglo-Portuguese regulars, drained the empire of men and money and provoked resentment against Napoleonic rule, including in France where the wars had hitherto impacted relatively lightly. Austria was encouraged to re-enter the fray. Her forces destroyed the myth of French invincibility at Aspern-Essling (May 21–22, 1809), though defeat at Wagram (July 6, 1809) led to a humiliating peace settlement and the marriage of Napoleon to an Austrian princess, Marie-Louise, in 1810. (As he told the divorced Josephine, he needed an heir.) Relations with Russia worsened over the latter's failure to enforce the Blockade, and in 1812 Napoleon embarked upon the Russian campaign that would end in humiliation and the destruction of most of the Grande Armée. The retreat from Moscow was the prelude to defeat in the 1813–1814 campaign at the hands of the Sixth Coalition comprising Russia, Prussia, Britain, Sweden, and, latterly, Austria, as well as some minor German states. The campaign was in many respects one of the most brilliant fought by Napoleon. Yet although Napoleon defeated the Allies at Lützen and Bautzen in May and at Dresden in August, his opponents were able to pick off his subordinate commanders, who were beaten at Katzbach, Kulm, and elsewhere. Eventually, the emperor was himself defeated at the epic three-day engagement at Leipzig, the so-called Battle of the Nations (October 1813), which was the prelude to an Allied invasion of France. Napoleon continued to achieve a series of local victories, leading him to reject the peace terms offered at Chaumont, but he was heavily out numbered and unable to prevent the Allies from occupying Paris at the end of March. Faced with a withdrawal of support from his generals and marshals, on April 11 Napoleon abdicated unconditionally and went into exile on the Mediterranean island of Elba. However, encouraged by reports of the unpopularity of the restored Bourbons—the brother of the executed Louis XVI had been put on the throne as Louis XVIII—he returned to France in March 1815. In the period that was dubbed the Hundred Days bythe Prefect of the Seine, Napoleon sought to permanently recover power, raising an army and, less successfully, offering a reformed Constitution in the hope of rallying political support. Although his campaign against the combined forces of the Seventh Coalition began promisingly, he was defeated at Waterloo (June 15, 1815) and permanently exiled to St. Helena. Napoleon's military record ensured that he would be an inspiration for generations to come. More controversially, he used his remaining years in exile, through comments recorded by the Comte de Las Cases, Montholon, Gourgaud, and others, to create an image of himself as a liberal reformer who had sought to unify Europe.